Re: Hull Cleaning
Usually the discoloration is from algae. The way hulls are cleaned in our area is spraying a muriatic acid solution on the hull, then, following it up with a pressure washer before the solution dries (avoid decals, use a vinyl cleaner on them. Also be careful with the pressure washer around decals, avoid them or hit them at 90 ? angles only!). If applied within say a year or so, hulls come out looking like new most of the time. You can do it yourself, or most marinas offer this service, usually at not to crazy prices (of course, now having said that??..).
The discoloration may be harder to get off completely if the boat has been out of the water for more than a year. Not cleaning the hull for more than a year or two gives the algae a better chance to permeate the gel coat and set in, especially when it?s not in the water. If too much time has gone by it makes it almost impossible to get it completely out. When the boat is in the water the algae tends to stays more on top of the gel cote. Cleaning the boat right after pulling it out to prep it to store for the winter, or when you pull it out of storage and prep it for the new season, gives the best success rate. Waxing the hull to prevent this condition makes the discoloration problem worse (although you would probably think the opposite, I did, also this pertains only to fiberglass, not ). For some reason, wax helps to provide an easier way for algae to permeate the gel cote.
So, the longer that discoloration has been on the hull and out of the water (and hopefully the hull wasn?t waxed), the harder it will be to restore it to like new condition. The only way to find out is to go through the cleaning process.